Interplay between magnetic properties and thermoelectricity in misfit and Na cobaltates

Abstract

We present a comparative study of CoO2 layers in the Bi-misfit and NaxCoO2 cobaltates. Co NMR measures the intrinsic susceptibility of the Co layers and is not affected by spurious contributions. At low dopings where room-temperature thermopower (TEP) is large, Curie-Weiss susceptibilities are observed in both materials. But NMR and muSR experiments find neither charge nor spin order down to low temperatures in Bi-misfit, in contrast to the case of NaxCoO2. This demonstrates that metallicity, charge and magnetic orders are specific of the Na layers in NaxCoO2 whereas strong correlations are generic of the cobaltates physics and could explain the large TEP.

4 pages

References in corpus (5)

• Scaling behavior in thermoelectric misfit cobalt oxides
• Evidence of a single nonmagnetic Co3+ state in the Na1CoO2 cobaltate
• Na Induced Correlations in Na${}_x$CoO${}_2$
• Direct observation of strong correlations near the band insulator regime of Bi misfit cobaltates
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Cited by in corpus (7)

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• From quantum criticality to enhanced thermopower in strongly correlated layered cobalt oxide
• Spin polaron theory for the photoemission spectra of layered cobaltates
• Magnetic field dependent specific heat and enhanced Wilson ratio in strongly correlated layered cobalt oxide
• Dual electronic states in thermoelectric cobalt oxide
• ω/T scaling of the optical conductivity in strongly correlated layered cobalt oxide